Stamp



FIG. 1 is a front left perspective view of a stamp showing our new design;

FIG. 2 is a front right perspective view thereof;

FIG. 3 is a plan view thereof; and,

FIG. 4 is a rear side elevation view thereof.

The broken lines shown in the views are included for the purpose of illustrating portions of the stamp that form no part of the claimed design. 

CLAIM The ornamental design for a stamp, as shown and described. 